parsing.hpp

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                                  || *start== const_or_not(fac).widen( 'L') 
                                  || *start== const_or_not(fac).widen( 'h')) )
            ++start;
        if( start>=last) {
            maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
            return true;
        }

        if( in_brackets && *start== const_or_not(fac).widen( '|') ) {
            ++start;
            return true;
        }
        switch ( wrap_narrow(fac, *start, 0) ) {
        case 'X':
            fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
        case 'p': // pointer => set hex.
        case 'x':
            fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
            fpar->fmtstate_.flags_ |= std::ios_base::hex;
            break;

        case 'o':
            fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
            fpar->fmtstate_.flags_ |=  std::ios_base::oct;
            break;

        case 'E':
            fpar->fmtstate_.flags_ |=  std::ios_base::uppercase;
        case 'e':
            fpar->fmtstate_.flags_ &= ~std::ios_base::floatfield;
            fpar->fmtstate_.flags_ |=  std::ios_base::scientific;

            fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
            fpar->fmtstate_.flags_ |=  std::ios_base::dec;
            break;
      
        case 'f':
            fpar->fmtstate_.flags_ &= ~std::ios_base::floatfield;
            fpar->fmtstate_.flags_ |=  std::ios_base::fixed;
        case 'u':
        case 'd':
        case 'i':
            fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
            fpar->fmtstate_.flags_ |=  std::ios_base::dec;
            break;

        case 'T':
            ++start;
            if( start >= last)
                maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
            else
                fpar->fmtstate_.fill_ = *start;
            fpar->pad_scheme_ |= format_item_t::tabulation;
            fpar->argN_ = format_item_t::argN_tabulation; 
            break;
        case 't': 
            fpar->fmtstate_.fill_ = const_or_not(fac).widen( ' ');
            fpar->pad_scheme_ |= format_item_t::tabulation;
            fpar->argN_ = format_item_t::argN_tabulation; 
            break;

        case 'G':
            fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
            break;
        case 'g': // 'g' conversion is default for floats.
            fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
            fpar->fmtstate_.flags_ |=  std::ios_base::dec;

            // CLEAR all floatield flags, so stream will CHOOSE
            fpar->fmtstate_.flags_ &= ~std::ios_base::floatfield; 
            break;

        case 'C':
        case 'c': 
            fpar->truncate_ = 1;
            break;
        case 'S':
        case 's': 
            if(precision_set) // handle truncation manually, with own parameter.
                fpar->truncate_ = fpar->fmtstate_.precision_;
            fpar->fmtstate_.precision_ = 6; // default stream precision.
            break;
        case 'n' :  
            fpar->argN_ = format_item_t::argN_ignored;
            break;
        default: 
            maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
        }
        ++start;

        if( in_brackets ) {
            if( start != last && *start== const_or_not(fac).widen( '|') ) {
                ++start;
                return true;
            }
            else  maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
        }
        return true;
    }
    // -end parse_printf_directive()

    template<class String, class Facet>
    int upper_bound_from_fstring(const String& buf, 
                                 const typename String::value_type arg_mark,
                                 const Facet& fac, 
                                 unsigned char exceptions) 
    {
        // quick-parsing of the format-string to count arguments mark (arg_mark, '%')
        // returns : upper bound on the number of format items in the format strings
        using namespace boost::io;
        typename String::size_type i1=0;
        int num_items=0;
        while( (i1=buf.find(arg_mark,i1)) != String::npos ) {
            if( i1+1 >= buf.size() ) {
                if(exceptions & bad_format_string_bit)
                    boost::throw_exception(bad_format_string(i1, buf.size() )); // must not end in ".. %"
                else break; // stop there, ignore last '%'
            }
            if(buf[i1+1] == buf[i1] ) {// escaped "%%"
                i1+=2; continue; 
            }

            ++i1;
            // in case of %N% directives, dont count it double (wastes allocations..) :
            i1 = detail::wrap_scan_notdigit(fac, buf.begin()+i1, buf.end()) - buf.begin();
            if( i1 < buf.size() && buf[i1] == arg_mark )
                ++i1;
            ++num_items;
        }
        return num_items;
    }
    template<class String> inline
    void append_string(String& dst, const String& src, 
                       const typename String::size_type beg, 
                       const typename String::size_type end) {
#if !defined(BOOST_NO_STRING_APPEND)
        dst.append(src.begin()+beg, src.begin()+end);
#else
        dst += src.substr(beg, end-beg);
#endif
    }

} // detail namespace
} // io namespace



// -----------------------------------------------
//  format :: parse(..)

    template<class Ch, class Tr, class Alloc>
    basic_format<Ch, Tr, Alloc>& basic_format<Ch, Tr, Alloc>:: 
    parse (const string_type& buf) {
        // parse the format-string 
        using namespace std;
#if !defined(BOOST_NO_STD_LOCALE)
        const std::ctype<Ch> & fac = BOOST_USE_FACET( std::ctype<Ch>, getloc());
#else
        io::basic_oaltstringstream<Ch, Tr, Alloc> fac; 
        //has widen and narrow even on compilers without locale
#endif

        const Ch arg_mark = io::detail::const_or_not(fac).widen( '%');
        bool ordered_args=true; 
        int max_argN=-1;

        // A: find upper_bound on num_items and allocates arrays
        int num_items = io::detail::upper_bound_from_fstring(buf, arg_mark, fac, exceptions());
        make_or_reuse_data(num_items);

        // B: Now the real parsing of the format string :
        num_items=0;
        typename string_type::size_type i0=0, i1=0;
        typename string_type::const_iterator it;
        bool special_things=false;
        int cur_item=0;
        while( (i1=buf.find(arg_mark,i1)) != string_type::npos ) {
            string_type & piece = (cur_item==0) ? prefix_ : items_[cur_item-1].appendix_;
            if( buf[i1+1] == buf[i1] ) { // escaped mark, '%%' 
                io::detail::append_string(piece, buf, i0, i1+1);
                i1+=2; i0=i1;
                continue; 
            }
            BOOST_ASSERT(  static_cast<unsigned int>(cur_item) < items_.size() || cur_item==0);

            if(i1!=i0)
                io::detail::append_string(piece, buf, i0, i1);
            ++i1;
            it = buf.begin()+i1;
            bool parse_ok = io::detail::parse_printf_directive(
                it, buf.end(), &items_[cur_item], fac, i1, exceptions());
            i1 = it - buf.begin();
            if( ! parse_ok ) // the directive will be printed verbatim
                continue; 
            i0=i1;
            items_[cur_item].compute_states(); // process complex options, like zeropad, into params

            int argN=items_[cur_item].argN_;
            if(argN == format_item_t::argN_ignored)
                continue;
            if(argN ==format_item_t::argN_no_posit)
                ordered_args=false;
            else if(argN == format_item_t::argN_tabulation) special_things=true;
            else if(argN > max_argN) max_argN = argN;
            ++num_items;
            ++cur_item;
        } // loop on %'s
        BOOST_ASSERT(cur_item == num_items);
    
        // store the final piece of string
        {
            string_type & piece = (cur_item==0) ? prefix_ : items_[cur_item-1].appendix_;
            io::detail::append_string(piece, buf, i0, buf.size());
        }
    
        if( !ordered_args) {
            if(max_argN >= 0 ) {  // dont mix positional with non-positionnal directives
                if(exceptions() & io::bad_format_string_bit)
                    boost::throw_exception(io::bad_format_string(max_argN, 0));
                // else do nothing. => positionnal arguments are processed as non-positionnal
            }
            // set things like it would have been with positional directives :
            int non_ordered_items = 0;
            for(int i=0; i< num_items; ++i)
                if(items_[i].argN_ == format_item_t::argN_no_posit) {
                    items_[i].argN_ = non_ordered_items;
                    ++non_ordered_items;
                }
            max_argN = non_ordered_items-1;
        }
    
        // C: set some member data :
        items_.resize(num_items, format_item_t(io::detail::const_or_not(fac).widen( ' ')) );

        if(special_things) style_ |= special_needs;
        num_args_ = max_argN + 1;
        if(ordered_args) style_ |=  ordered;
        else style_ &= ~ordered;
        return *this;
    }

} // namespace boost


#endif //  BOOST_FORMAT_PARSING_HPP